New techniques for fabricating structures with nanometer dimensions are critically important to advances in nanoscience and technology. As the demand for smaller electronic devices, and biological analysis apparatus, has increased, a need has been created for improved fabrication processes for making such devices. The processes may be utilized in the fabrication of electronic, magnetic, mechanical, and optical devices, as well as devices for biological and chemical analysis. The processes may be used, for example, to define the features and configurations of microcircuits, as well as, the structure and operating features of optical waveguides and components.
These processes may also play a crucial role in the semiconductor industry, replacing conventional projection mode photolithography, whose practical limits make it impossible to reach resolution at sizes less than 45 nanometers. Projection mode photolithography is a method of patterning features, wherein a thin layer of photoresist is applied to a substrate surface and selected portions of the resist are exposed to a pattern of light. The resist is then developed to reveal a desired pattern of exposed substrate for further processing, such as etching. A difficulty with this process is that resolution is limited by the wavelength of the light, scattering in the resist and substrate, and the thickness and properties of the resist. As a result, projection mode photolithography cannot be utilized to economically create feature sizes less than 100 nanometers.
Next generation lithography (NGL) methods including e-beam, dip pen and nano-imprint techniques are being explored. E-beam methods include creating patterns in polymers, called resists, and using microlithography based on short wavelength UV radiation or electron beams. Patterns are formed due to a change in solubility of polymers from exposure to the imaging radiation with the use of a solvent to remove a portion of the polymer film. However, large scale commercially producing dimensions on a length-scale of less than 100 nm using these techniques is costly and can be carried out using very special imaging tools and materials.
Of the NGL techniques, those that use molds to imprint features into thin polymer films have attracted considerable attention. Although the well defined optics associated with photolithographic techniques allows their resolution to be specified accurately, the resolution limits of NGLs based on nano-molding are much more difficult to determine. The uncertain polymer physics that governs the molding process and the absence of a reliable means to evaluate the resolution at less than 5 nanometers in length represent some limits on current techniques.
There is therefore, a need in the art for a nano-molding process that solves the problems outlined above and can be utilized to produce relief structures that have lateral and vertical dimensions less than 10 nanometers. There is also a need in the art for such a process that allows for verification of dimensions on a part produced by the process.